In operations in the area of the hip and, in particular, for preparing a surgical incision for inserting an artificial hip joint, such as, for example, for determining the size and position of an implant, it is preferable, in addition to determining the position and geometry of the hip, to also determine the position and geometry or dimensions of the femur. In particular, the proximal femur and the femur head are of importance to a surgeon for preparing or planning to insert an artificial joint head. In order to ensure that the artificial hip joint functions correctly and to enable a long service life for the artificial joint, the femoral component of the artificial hip joint should be positioned in the bone structure of the femur in a particular position with respect to the shaft axis and the femur neck axis. In particular, a good fitting of the femur implant in the femur neck and/or in the shaft channel is important for a good load distribution of the implant.
During a surgical incision, a surgeon usually relies on a visual assessment of the exposed bone structure to determine the fitting of the femur implant. However, surgical incisions are increasingly performed in such a way that only the smallest possible areas are cut open, such that it is no longer possible to determine the position of an implant by visual assessment alone. Two-dimensional x-ray images are often used to obtain additional information regarding the desired position of implants relative to the bone. However, a partially grainy, two-dimensional x-ray image only provides a surgeon with a mapping of the body structure in question that is roughly shown by different grey scales. From such images, it is difficult to precisely determine the three-dimensional coordinates for correctly positioning an implant in the bone.
Therefore, computer tomography (CT) recordings of the body structure in question are often generated. However, CT recordings subject the patient to a significantly higher radiation exposure relative to the two-dimensional x-ray recordings mentioned above.